CASE CLOSED

MURDER BOOK BINGO I watch a fair number shows of  the "Unsolved Murder" genre, mostly on ID DISCOVERY.   Where some newby detective is handed boxes of crime scene evidence from a 20 year-old unsolved homicide, and  tasked with solving it.  The crimes are invariably solved when the detective realizes that this stuff was collected before DNA was invented, but now it has, so he sends it for analysis.  The perp, now living in Florida with his wife and 6 children, is arrested.  Which begs the question: Why doesn't every police department in the USofA go through old case files and, just for the hell of it,  send blood, semen, spit samples to the crime lab?  Like, right now? Duh. Thank you.  I await my Nobel Prize.